It is proposed to purchase a JEOL, JEM-100CX TEMSCAN Analytical Electron Microscope and place the instrument on joint use to facilitate the morphological and analytical studies now being carried out under the auspices of several NIH grants which support the primary users. One project involves analyses of cell surface molecules on developing neurons in culture by scanning electron microscopy (SEM) using immunocytochemistry and other cytochemical procedures. This project also involves the examination of synaptogenesis in neuronal cultures using backscattered electron imaging (BEI) to detect synapses that have been selectively stained with high atomic number elements. Conventional transmission electron microscopy (CTEM) and scanning transmission electron microscopy (STEM) will be used to study intracellular structure in developing axons and dendrites of cultured neuronal cells. A second project will use CTEM and STEM to examine the integrity of intercellular junctions of pulmonary endothelial cells and the ultrastructure of the epithelial cells during the experimental induction of neurogenic pulmonary edema. A third project will use CTEM and STEM to study the effects of standard perfusion media on the in vitro swelling of corneas. The organization of collagen in the extracellular matrix and the ultrastructure of keratocytes in the posterior stroma will be examined as various components of the extracellular matrix are extracted. A fourth project will use CTEM to assess the identity of and the retention of differentiated morphology of several cell lines to be established in tissue culture from tissues of animals of different ages. Changes in these and biochemical and immunochemical characteristics as the result of aging in culture will be determined and correlated to the source and age of the tissues used to establish the cultures. The JEOL TEMSCAN will permit us to carry out all of these studies on a single high resolution instrument. No instrument is now available to us which can function as a high resolution STEM.